I dunno.... ClipStudioPaintEx has a push button item that converts photoreal graphics to Japanese Manga and Western Toon style. Poser has Sketch Rendering which creates NPR art as well. Cycles has NPR shaders devised by the Blender3D Cycles NPR community, but those do need some elbow grease. Any improvement to output would be welcomed by NPR art creators (me being one of them)

Eternal Hobbyist